Casting materials used in orthopedic applications include plaster of Paris, variations thereof and curable resin systems. Casts are frequently used in combination with a soft layer of padding applied between the load-bearing casting material and the skin. Most of the plaster of Paris and curable resin systems are cured by water or aqueous catalyst systems. Generally, curing is carried out by immersing or otherwise soaking the casting material in water prior to application to the body. This process can result in wetting of the skin and any cast padding used. In use, the cast may be splashed, immersed or otherwise exposed to water, resulting in wetting of the underlying padding. Furthermore, the patient may transpire or sweat under the cast and create a humid environment under the cast that can serve as a breeding ground for microorganisms and cause serious skin breakdown. Therefore, if wetted, it is desirable that the cast padding dry as rapidly and completely as possible.
Fabrics used with casts for conventional padding materials have included cotton, foams, synthetics and wool. The major functions of the padding materials are cushioning, filing and thermal insulation. Medical uses for the padding materials include applying or relieving pressure and absorption of excess moisture. However, most padding materials lose their functionality when immersed in water.
Furthermore, conventional padding materials such as cotton and polyester are water absorbent with high apparent surface energy and tend to compress and hold water when wetted. Padding that remains wet for prolonged period scan cause skin irritation, maceration, infection and discomfort after a relatively short period of time (e.g., within 24 hours) since microorganisms such as bacteria and fungi can thrive in this environment. These conditions may also result in foul odors. Drying out wet casts with forced hot air, such as a hair dryer, is a prolonged and tedious process. Alternatively, plastic bags of various shapes can be used to prevent the cast from getting wet, but they prevent the use of any form of hydrotherapy of the injured limb.
Cast padding systems that provide microporous films, non-porous films, and composite structures adjacent to the skin are also known. Such films can feel clammy and uncomfortable for the patient. Furthermore, these systems are often not self adherent, and/or bulky, and require special techniques to wrap the limb.
It is desirable to provide a casting system with padding materials that dry rapidly if exposed to water. It is also desirable that such padding materials permit intentional wetting of the cast, for example, during bathing or discretionary exposure to water. It is also desirable that such padding materials be very comfortable for the patient to wear and/or easy for the clinician to apply.